Structure-related luminescent properties induced by doping in Sm-doped SnO2 hollow spheres

Despite the significant amount of research on the sensitization of positive trivalent lanthanide (Ln(3+)) ions doped into semiconductor nanocrystals, it is unclear how the local structure of doped ions affects luminescence. The difficulty is that an actual low-dimensional doping system is often a mixture of surface doping and bulk doping, and its distribution characteristics are sensitively dependent on external factors. The aim of this work on Sm3+ ion-doped SnO2 hollow spheres is to investigate the doping-related structural and luminescent properties, distinguish the luminescence mode characteristics subject to surface doping and bulk doping (or core doping), and depict the relative ratio change of the two doping sites caused by doping. Due to the synergistic or competitive interactions of quantum confinement effects, stress effects, and surface defects, it is found that the crystallite size, Raman mode, band gap, and luminescence properties exhibit specific changes with increasing doping. The optimal doping occurs at 4.5%, which corresponds to the best crystallization and maximized sensitized emission. The asymmetry ratio is used to determine the ratio of surface doping and bulk doping and its variation with doping concentration, which increases with decreasing doping, especially at low doping levels, indicating that the contribution of surface doping is significant at low doping level. This work provides a unique perspective to quantitatively study the sensitized luminescence characteristics of Sm3+ doped SnO2 nano-hollow spheres, which will provide a solution path for controlled sensitized emission.